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October 12, 2007

Atomic orbitals change at the interface of certain types of nanostructures

Until now, materials science researchers believed that an electron's charge and spin influenced the characteristics of conventional bulk materials. Atomic orbitals, which consist of the patterns of electron density that may be formed in an atom, were previously thought to be inactive.

Chakhalian's work has focused on what happens at the interface between two different materials - for instance, superconductors and ferromagnets, two materials with properties that were thought to be incompatible with each other in bulk. In 2006, he and his colleagues created the first high-quality material to have both superconducting and ferromagnetic properties, and they used that material in this experiment.

The researchers forced a high-temperature superconducting material containing copper oxide and a ferromagnetic material containing manganese oxide into unusual quantum states. Using a technique called resonant X-ray absorption, they were able to "look" at the atomic orbitals at the interface and determine their symmetry in a non-destructive way.

They found that the atomic orbitals changed the nature of their symmetry at the interface and created a covalent bond between the copper and manganese atoms. This bonding does not exist in the bulk of the individual materials

"When you merge these two materials, the atomic orbitals at the interface become important. They start contributing to the electronic properties of the material," Chakhalian said. "This opens a new way of designing materials. We can design quantum materials with engineered physical properties."

The discovery may allow researchers to manipulate nanoscale superconductivity at the interface - opening the possibility of creating room-temperature superconductors.

Generators that use superconducting materials generate electricity extremely efficiently, at half the size of conventional generators. General Electric estimates the potential market for superconducting generators to be between $20 billion and $30 billion over the next decade.

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